This invention relates to data recording drives and, more particularly, to a removable cartridge and drives for data recording thereon.
Removable magnetic disk cartridges generally employ a protective shell that surrounds and protects a data recording medium from dust, impact, and other data-corrupting influences. A well-known industry trend has been toward increasing data storage capacity. Greater data capacity usually is accomplished by more densely arranging tracks on the surface of the data storage medium. A competing industry trend is toward a storage medium having a smaller form factor. The smaller form factor has resulted in efforts to conserve space within the cartridge in order to maximize the surface area of the data storage medium. Furthermore, a smaller cartridge requires even higher track density to maintain or increase data storage capacity compared with a larger cartridge.
Unfortunately, the higher storage density generally makes a recording medium more sensitive to contamination by dust particles. That is, a certain quantity and size of particulate matter that may be tolerated by a similar data recording medium may cause contamination of a data storage media that have more densely concentrated tracks. Contamination may cause, for example, interruption of data reading or recording, lower accuracy of head positioning, and diminished reliability. This greater sensitivity to particulate matter requires better sealing than prior art cartridges have provided.
A cartridge that protects a recording medium and provides sealing is described in U.S. Pat. No. 5,570,252 Sumner et al., which is assigned to the assignee of the present invention. The Sumner cartridge has a rigid shell, a magnetic medium, and a flexible door that covers an opening through which drive heads pass. The flexible door slides in a curved track along the cartridge wall, thereby efficiently using space within the cartridge by eliminating any dead space through which a hinged, rigid door would sweep. Because the disk substantially fills the space inside, the Sumner cartridge efficiently uses space.
Particulate matter may originate from sources either outside of the cartridge or from moving parts within the cartridge. For example, conventional cartridges have moving parts that generate particles as surfaces abrade one another. Furthermore, conventional cartridge shells often have internal mechanisms that clamp the data recording medium to protect it from shock and vibration while the cartridge is outside the drive. The internal mechanisms are typically retractable to allow the medium to rotate while the cartridge is inside the drive. Unfortunately, the internal mechanisms are expensive to manufacture and the moving parts that form the internal mechanisms produce particulate matter. Furthermore, the internal clamping mechanisms are often more delicate than the other parts of the shell and are therefore subject to breaking. For example, U.S. Pat. No. 5,235,481 (Kamo) describes a removable cartridge that has a protective shell around a data recording medium and provisions to seal dust from the medium. Unfortunately, the Kamo cartridge has numerous internal parts that make the cartridge more susceptible to damage if jolted. An additional drawback of the Kamo cartridge is that the internal parts are complicated and costly to produce. Furthermore, the movement of the shutter and the internal parts generate particulate matter within the shell that can harm the function of the data recording medium.
Some conventional protective shells enclose a disk while using few internal parts. However, these protective cases typically require a user to remove a cover while the case is outside of the drive. Removing the cover typically exposes the medium to dust particle contamination in the ambient air. For example, U.S. Pat. No. 5,475,672 (Yamashita) describes a cartridge having provisions for securing a rigid disk within a two-piece shell. The top portion of the two-piece shell, which itself is a protective case, may be inserted into a corresponding disk drive. A hinged lid on the top portion allows access to the disk. However, a disk in the Yamashita cartridge is unprotected from particulate contamination in two ways: first, the disk is removable by the user, which subjects the disk to the ambient atmosphere, and, second, the case top portion has a drive opening that is uncovered when the top portion is detached from the bottom portion of the case. Furthermore, particulates generated from the hinge and other abrading parts may foul the medium because the medium is not sealed therefrom.
Some cartridges, in contrast to the Yamashita cartridge, have a non-removable data recording medium housed within a cartridge. Often, the cartridge is opened by a mechanism within the drive as the cartridge is loaded into the drive. U.S. Pat. No. 5,175,726 (Imokawa) describes such a protective cartridge for a non-removable optical disk. The Imokawa cartridge protects an optical disk by providing a non-recording surface around the perimeter of the disk. A shell provides space around the disk to permit the disk to move freely within the shell, although only the non-recording portion of the disk and the hub contact the shell. Unfortunately, the contact between the case and the non-recording portion of the disk generates particulate matter within the shell. Moreover, the Imokawa cartridge has a shutter that slides over an opening in the case, thereby generating particulate matter within the shell, which could contaminate the medium.
Regarding disk drives for operating removable cartridges, vertical height restrictions make thinner disk drives advantageous. Disk drive height for removable cartridge drives depends, in part, on overall spindle motor height, which is primarily dictated by bearing thickness, bearing spacing, and height of the engagement feature for engaging and locating the disk. Referring to FIG. 24, a conventional spindle motor 201 is shown engaged with a conventional disk hub 200 having a hole 218. Spindle motor 201 includes a spindle pin 202, a rotor 204, an upper bearing 210, a lower bearing 212, and clamp magnets 214. Rotor 204 is attached to pin 202, which is supported by bearings 210 and 212. Hole 218 typically is approximately 5 mm diameter, which is smaller than conventional spindle motor bearing 140 outside diameter.
As conventional spindle motor 201 is raised toward conventional hub 200, spindle motor pin 202, which has approximately 5 mm outside diameter, engages with hole 218 of cartridge hub 200 and aligns the hub 200 with spindle motor 201. Overall spindle motor height typically includes, therefore, electric motor height (including motor bearings 210 and 212) plus height of the pin 202 protruding above motor bearings 210 and 212.
There is a need, therefore, for a data recording cartridge and disk drive that overcome the disadvantages of the prior art.